Rocker arm assembly

Abstract

A combined exhaust and engine brake rocker arm assembly ( 20 ) configured to selectively open first and second exhaust valves ( 26, 28 ) includes a rocker arm body ( 40 ), an exhaust rocker arm assembly ( 16 ) formed in the rocker arm body ( 40 ), and a lost motion spigot assembly ( 56 ) including an adjustment nut ( 70 ) and guide ( 62 ) configured to receive a shaft assembly ( 60 ) for adjusting a lash of the lost motion spigot assembly ( 56 ). The shaft assembly is disposed within a bore ( 92 ) of the adjustment nut below an upper surface thereof, and an engine brake rocker arm assembly ( 18 ) is formed in the rocker arm body ( 40 ) and configured to operate in a collapse mode and a rigid mode. The lost motion spigot assembly ( 56 ) is configured to selectively engage a valve bridge ( 52 ) to open the first and second exhaust valves ( 26, 28 ), and the engine brake rocker arm assembly ( 18 ) is configured to selectively engage the valve bridge ( 52 ) to open only the first exhaust valve ( 26 ).

What is claimed is: 
     
       1. A combined rocker arm assembly for selectively opening first and second exhaust valves, the combined rocker arm assembly comprising:
 a rocker arm body; 
 an exhaust rocker arm assembly formed in the rocker arm body; 
 a lost motion spigot assembly operatively coupled to the exhaust rocker arm assembly via a first bore formed in the rocker arm body, the lost motion spigot assembly including an adjustment nut and a guide which cooperate so as to define an internal bore; 
 a shaft assembly arranged in the internal bore below an upper surface of the adjustment nut, the shaft assembly configured to adjust a lash of the lost motion spigot assembly; and 
 an engine brake rocker arm assembly formed in the rocker arm body, the engine brake rocker arm assembly configured to alternately operate in a collapse mode and a rigid mode, 
 wherein the lost motion spigot assembly is configured to selectively engage a valve bridge so as to open the first and second exhaust valves, 
 wherein the engine brake rocker arm assembly is further configured to selectively engage the valve bridge so as to open only the first exhaust valve when operating in the rigid mode, 
 wherein the guide includes a first step configured to interface with the adjustment nut, and a second step configured to interface with a biasing mechanism, and 
 wherein the first bore includes a shoulder configured to cooperate with the second step so as to define a first biasing mechanism seat for the biasing mechanism. 
 
     
     
       2. The combined rocker arm assembly of  claim 1 , wherein the adjustment nut includes a T-shaped cross-section. 
     
     
       3. The combined rocker arm assembly of  claim 2 , wherein a portion of the internal bore corresponding to an upper flange portion of the T-shaped cross-section is not threaded. 
     
     
       4. The combined rocker arm assembly of  claim 2 , wherein the shaft assembly includes an upper shaft and a lower shaft collectively extending through the guide, and
 wherein the upper shaft is threaded to a remaining portion of the internal bore at the adjustment nut. 
 
     
     
       5. The combined rocker arm assembly of  claim 1 , further comprising a cap coupled to the exhaust rocker arm assembly, the cap configured as a second biasing mechanism seat for the biasing mechanism. 
     
     
       6. The combined rocker arm assembly of  claim 1 , wherein the guide further includes a third step configured to engage a stop surface formed on the rocker arm body. 
     
     
       7. The combined rocker arm assembly of  claim 6 , wherein the second step is set radially inward of the third step, and the first step is set radially inward of the second step. 
     
     
       8. The combined rocker arm assembly of  claim 1 , wherein the engine brake rocker arm assembly includes an engine brake capsule configured to switch between a retracted position and an extended position,
 wherein the engine brake capsule does not engage the valve bridge when in the retracted position, and 
 wherein the engine brake capsule selectively engages the valve bridge when in the extended position so as to open the first exhaust valve. 
 
     
     
       9. The combined rocker arm assembly of  claim 8 , wherein the engine brake capsule includes an outer housing, a plunger, and a pin assembly. 
     
     
       10. The combined rocker arm assembly of  claim 9 , wherein the plunger is disposed in a lower chamber of the outer housing, and the pin assembly is at least partially disposed within an upper chamber of the outer housing. 
     
     
       11. The combined rocker arm assembly of  claim 10 , wherein the engine brake capsule further includes a check ball assembly disposed within the lower chamber, the pin assembly operatively associated with the check ball assembly so as to selectively enable a hydraulic fluid into the lower chamber such that the plunger moves from the retracted position to the extended position. 
     
     
       12. A valvetrain assembly comprising:
 a first engine valve; 
 a second engine valve; 
 a valve bridge operatively associated with the first and second engine valves; and 
 a combined rocker arm assembly configured to selectively open the first and second engine valves, the combined rocker arm assembly comprising:
 a rocker arm body; 
 an exhaust rocker arm assembly formed in the rocker arm body; 
 a lost motion spigot assembly operatively coupled to the exhaust rocker arm assembly via a first bore formed in the rocker arm body, the lost motion spigot assembly including an adjustment nut and a guide which cooperate so as to define an internal bore; 
 a shaft assembly arranged in the internal bore below an upper surface of the adjustment nut, the shaft assembly configured to adjust a lash of the lost motion spigot assembly; and 
 an engine brake rocker arm assembly formed in the rocker arm body, the engine brake rocker arm assembly configured to alternately operate in a collapse mode and a rigid mode, 
 wherein the lost motion spigot assembly is configured to selectively engage the valve bridge so as to open the first and second engine valves, 
 wherein the engine brake rocker arm assembly is further configured to selectively engage the valve bridge so as to open only the first engine valve when operating in the rigid mode, 
 wherein the adjustment nut includes a T-shaped cross-section, 
 wherein a portion of the internal bore at the adjustment nut is threaded except for a portion of the internal bore corresponding to an upper flange portion of the T-shaped cross-section that is not threaded, 
 wherein the shaft assembly includes an upper shaft and a lower shaft collectively extending through the guide, and 
 wherein the upper shaft is threaded to the threaded portion of the internal bore at the adjustment nut. 
 
 
     
     
       13. The valvetrain assembly of  claim 12 , wherein the guide includes:
 a first step configured to interface with the adjustment nut; 
 a second step configured as a seat for a biasing mechanism; and 
 a third step configured to engage a stop surface formed on the rocker arm body. 
 
     
     
       14. A valvetrain assembly comprising:
 a first engine valve; 
 a second engine valve; 
 a valve bridge operatively associated with the first and second engine valves; 
 a combined rocker arm assembly configured to selectively open the first and second engine valves, the combined rocker arm assembly comprising:
 a rocker arm body; 
 an exhaust rocker arm assembly formed in the rocker arm body; 
 a lost motion spigot assembly operatively coupled to the exhaust rocker arm assembly via a first bore formed in the rocker arm body, the lost motion spigot assembly including an adjustment nut and a guide which cooperate so as to define an internal bore; 
 a shaft assembly arranged in the internal bore below an upper surface of the adjustment nut, the shaft assembly configured to adjust a lash of the lost motion spigot assembly; and 
 an engine brake rocker arm assembly formed in the rocker arm body, the engine brake rocker arm assembly configured to alternately operate in a collapse mode and a rigid mode, 
 wherein the lost motion spigot assembly is configured to selectively engage the valve bridge so as to open the first and second engine valves, 
 wherein the engine brake rocker arm assembly is further configured to selectively engage the valve bridge so as to open only the first engine valve when operating in the rigid mode, 
 wherein the guide includes:
 a first step configured to interface with the adjustment nut; 
 a second step configured to interface with a biasing mechanism; and 
 a third step configured to engage a stop surface formed on the rocker arm body, 
 
 wherein the first bore includes a shoulder configured to cooperate with the second step so as to define a first biasing mechanism seat for the biasing mechanism, and 
 wherein the exhaust rocker arm assembly includes a cap configured as a second biasing mechanism seat for the biasing mechanism. 
 
 
     
     
       15. The valvetrain assembly of  claim 14 , wherein the second step is set radially inward of the third step, and the first step is set radially inward of the second step.